Diagnostic information gathered early on from a patient is vitally important to the ultimate outcome of orthodontic and orthognathic procedures, treating conditions such as mal-alignment and jaw disorders, and in making dental prostheses and restorations. Indirect restorations, such as crowns, are typically fabricated outside of the patient's mouth. Usually an initial process step, such as making an impression of the patient's maxillary arch is necessary to make a maxillary model. If the maxillary model is not properly oriented to the patient's face at the time the diagnostic information is gathered, then a technician cannot design the teeth with the patient's face/smile in mind. If the existing maxillary teeth alone are used and the maxilla is canted or the teeth offset (i.e. with respect to the face/cranium) the quality of any resulting restoration may be adversely compromised.
Presently available face bow devices are used to analyze a patient's occlusion with reference to their cranium, head and/or face from both an esthetic and functional point of view. The objective is to allow dentists to replicate the orientation of the patient's teeth with reference to their cranium, head and/or face in three planes on an articulator.
There are many face bow systems available, but they have many drawbacks as they are complex, time consuming, and uncomfortable for the patient. Further, they are costly to use and frustrating for most dental clinicians to work with. One such system, called the dento-facial analyzer, simplified the face bow process significantly. However, it features a bite fork with gripping wings that are difficult to manipulate in three dimensions. Such manipulation is often done while dental impression or bite registration material is setting while being held in the patient's mouth, adding further difficulty and discomfort to the process.
As a result, dentists often avoid using face bows because they are awkward to use by the dentist, unpleasant for the patient and prone to error. At the same time it is often essential in order to properly predict functional and esthetic outcomes. Past devices have been designed to use certain facial landmarks to determine bite plane orientation, (i.e. pupillary eye line (horizontal reference plane), tip of the nose (sagittal mid-plane), Frankfort-horizontal, etc.) Unfortunately, both such hard and soft tissue landmarks are inherently asymmetrical and do not reflect the true relationship of the facial features to the jaw. Moreover, if only those landmarks are utilized in determining the orientation of the desired occlusal or incisal plane, numerous esthetic and functional problems, including an undesirable occlusal or incisal plane, a slanted maxillary mid-line and gingival line may result. While landmarks are important, they should be treated as guidelines. It is believed that all those analog devices can confuse the ability to assess the symmetry of the face.
In an advance over known face bow systems, the present invention minimizes the amount of extra-oral mechanical-analog equipment, allowing the clinician and the patient to orient the patient's head into a desirably natural and, consequently, level position, with reference to both vertical and horizontal planes, at which point the digital orientation of the maxillary incisal and occlusal planes can be captured with a push of a button. In other cases it is not even necessary to move the patient's head. Further, the present invention will integrate quite easily into existing impression procedures which are used ubiquitously. In addition to every study model receiving a name and accompanying data, the dental professional will also receive a set of digital coordinates for use should the dentist need to relate the orientation of dentition to the face or cranium on an articulator. This information can accompany the models to a dental lab. There is no need for unwieldy analog face bows to accompany models. Further, the presently disclosed method does not require manipulation of external analog devices while impression material is setting. Virtually all analog manipulation is achieved indirectly (i.e. patient need not be present) with a mounting platform that can quickly replicate the maxillary incisal and occlusal planes in 3 dimensions and permit study casts to be transferred to any articulator the dentist or dental lab technician may be using. Alternatively, the digital information can be used with other digital systems and processes such as CAD CAM, digital impression techniques and 3D printing.